Rotary cutter for earth boring bits

ABSTRACT

A drill bit including a rotary cutter mounted on a bearing shaft which is supported between two legs of a saddle or cutter yoke wherein a lug portion of at least one of the saddle legs is weakened as by slotting the leg. An end of the bearing shaft is secured to the saddle leg by a bolt which draws the weakened lug portion into tight engagement with the shaft end whereby the shaft may be held against destructive chattering and against rotating with respect to the saddle leg. This abstract is neither intended to define the invention of the application which, of course, is measured by the claims, nor is it intended to be limiting as to the scope of the invention in any way.

Justman ROTARY CUTTER FOR EARTH BORING BITS [451 July 24, 1973 Primary Examiner-Charles J. Myhre Assistant Examiner-Barry Grossman Att0rneyC. M. Kucera [75] Inventor: Dan B. Justman, Houston, Tex. v

73 Assi nee: G. W. Mur h Industries Inc. 4 l l g Houston, TEX? [57] ABSTRACT [22] Filed. FBI 9 1972 A drill bit including a rotary cutter mounted on a bear- Y ing shaft which is supported between two legs of a sadl l PP N041 224,825 dle or cutter yoke wherein a lug portion of at least one of the saddle legs is weakened as by slotting the leg. An I n end of the bearing shaft is secured to the saddle leg by 5 308/15 gqki a bolt which draws the weakened lug portion into tight [58] Fie'ld "308/8 2 l engagement with the shaft end whereby the shaft may 61 3 be held against destructive chattering and against rotating with respect to the saddle leg. This abstract is nei- [56] References Cited ther intended to define the invention of the application which, of course, is measured by the claims, nor is it inv UNITED STATES PATENTS tended to be limiting as to the scope of the invention COSki in any way 1,444,074 2/1923 Hughes et al. 175/364 i 9 Claims, 2 Drawing Figures 4 Z r 1 :2 579 C v 4/ i k Q a Q I v l3 4/ Q Q /2! )g\ R 2 b V I PW cu T 14 \l T t \1 R0 74 T/ON w 20 5 T I l l C) IV l 23 h 24 IA l ll \)\(Z61 U j jl J L /6 i l DIRECT/ON or BIT ROTA-T/ON Pa tented July 24, 1973 DIRECTION OF BIT ROTATION ROTARY CUTTER FOR EARTH BORING BITS SUMMARY The present invention relates to earth boring drill bits of the rotary cutter type and to replaceable cutter assemblies therefor and to the mounting thereof on cutter supports.

In the drilling of earth bores for raises, wells, shafts, tunnels or the like, it is desirable to have a drill bit cutter assembly which is suitable for any of these purposes and which can readily be replaced without replacement of the entire drill bit.

It is an object of this invention to provide new and improved replaceable drill bit cutter assemblies which are adapted to fit on improved cutter supports mounted on a bit head. 1

Another object is to provide a new and improved cutter assembly and support therefor which assembly may be disposed between .cutter support legs of a saddle wherein the bearing shaft may have ends secured to the support to prevent the shaft from turning about its own axis and to prevent or alleviate relative movement between the shaft and the support.

BRIEF DESCRIPTION OF THE DRAWINGS DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawings, a cutter assembly is shown mounted on a steel cutter support or saddle 11.

The saddle 11 has a base 12 which may be welded or otherwise secured to a bit head (not shown). The cutter assembly 10 includes a steel rotary cutter 13 which is rotatably mounted on suitable bearings on a bearing shaft 14, as is well known in the art.

The saddle 11 includes an inner leg 15 and an outer leg 16. The bearing shaft 14 extends between the legs 15 and 16 and at least one end of the shaft 14 has flat surfaces 17,18 and 19 fitting closely with corresponding flats 17a, 18a and 19a of the leg 16 to hold the shaft 14 against turning on its axis.

The shaft 14 has a bore 20 therethrough and lugs 21 and 22 of the leg 16 have bores 23 and 24 aligned with bore 20. A bolt 25 extends through bores 23, 20 and Adjacent the lug 21, the leg 16 has a slot 26 therethrough extending toward the base 12 to a stress relief hole 27. This slot provides some flexibility to the ing 21 by reducing the bending strength thereof so that when the bolt 25 is tightened, the shaft 14 is tightly engaged by the lugs 21 and 22 to prevent rotation of the shaft about its axis and to prevent chattering or hammering between the shaft 14 and the bit leg 16 during the drilling operation.

While the end of the shaft 14 is here shown as having a rectangular shape, it will be apparent that various configurations may be used, and because the invention provides such a tight fit between the shaft and the leg, it is believed that the end of the shaft could be round and still provide a satisfactory attachment to the saddle leg.

It will be apparent that with the improved cutter support of the invention, a metal to metal fit is obtained between the shaft 14 and the lugs 21 and 22 without the necessity of holding extremely close and impractical machining tolerances between these parts.

Also, while the slot 26 is shown as being adjacent the leading saddle lug 21 with respect to the direction of rotation of the drill bit, it will be apparent that a slot 26a could be provided adjacent the trailing lug 22 or in some position between the two lugs of the saddle leg,

as at 26b.

The structure of the preferred embodiment has been successfully proven in actual drilling operations in the field.

The foregoing disclosure and description of the invention are illustrative and explanatory thereof, and various changes in the size, shape, locations and materials, as well as in the details of the illustrated construction, may be made within the scope of the appended claims without departing from the spirit of the invention.

What is claimed is:

1. A drill bit cutter assembly comprising:

, a saddle having a base and space-apart legs,

a bearing shaft extending between said legs,

a roller cutter rotatably mounted on said shaft between said legs,

the legs each having an opening into which the ends of said shaft are disposed,

the said legs having lug portions on the front and rear sides of said shaft with respect to the direction of rotation of the drill bit,

said saddle having slot means formed therein to provide flexibility to at least one of said lug portions, and

means securing the lug portions and the shaft tightly together.

2. A drill bit cutter assembly according to claim 1 wherein said slot means is located in the leg between said lug portion extending toward the base of said saddle.

3. A drill bit cutter-assembly according to claim 1 wherein the means to provide flexibility comprises a slot in the leg near the front lug portion, and a slot in the leg near the rear lug portion.

4. A drill bit cutter assembly according to claim 1 wherein an end of said bearing shaft is non-circular in cross section.

5. A drill bit cutter assembly according to claim 1 wherein an end of saidbearing shaft -is rectangular in cross section.

6. A drill bit cutter assembly according to claim 1 wherein the securingmeans includes a nut and bolt.

7. A drill bit cutter assembly according to claim 2 wherein v the slot is adjacent the rear lug portion.

8. A drill bit cutter assembly according to claim 1 wherein the slot is located between the front-and rear lug portions. v

9. A drill bit cutter assembly according to claim 2 wherein the slot is adjacent the front lug portion. 

1. A drill bit cutter assembly comprising: a saddle having a base and space-apart legs, a bearing shaft extending between said legs, a roller cutter rotatably mounted on said shaft between said legs, the legs each having an opening into which the ends of said shaft are disposed, the said legs having lug portions on the front and rear sides of said shaft with respect to the direction of rotation of the drill bit, said saddle having slot means formed therein to provide flexibility to at least one of said lug portions, and means securing the lug portions and the shaft tightly together.
 2. A drill bit cutter assembly according to claim 1 wherein said slot means is located in the leg between said lug portion extending toward the base of said saddle.
 3. A drill bit cutter assembly according to claim 1 wherein the means to provide flexibility comprises a slot in the leg near the front lug portion, and a slot in the leg near the rear lug portion.
 4. A drill bit cutter assembly according to claim 1 wherein an end of said bearing shaft is non-circular in cross section.
 5. A drill bit cutter assembly according to claim 1 wherein an end of said bearing shaft is rectangular in cross section.
 6. A drill bit cutter assembly according to claim 1 wherein the securing means includes a nut and bolt.
 7. A drill bit cutter assembly according to claim 2 wherein the slot is adjacent the rear lug portion.
 8. A drill bit cutter assembly according to claim 1 wherein the slot is located between the front and rear lug portions.
 9. A drill bit cutter assembly according to claim 2 wherein the slot is adjacent the front lug portion. 